Note: Descriptions are shown in the official language in which they were submitted.
CA 02740441 2011-05-17
LOW EMISSIONS HYBRID VEHICLE
BACKGROUND
100011 The present application relates generally to the field of vehicle power
systems.
More specifically, the present application relates to power systems for medium-
duty and
heavy-duty vehicles.
[00021 Referring to FIG. 1, a conventional vehicle power system 10 is shown.
The system
includes a single main power plant or power source 12. For medium and heavy
duty
trucks, the power source 12 is typically a diesel engine, but in other
embodiments may also
be a gasoline engine or another suitable portable power source. The power
source 12 drives
the wheels 14 to propel the vehicle. Typically, the output shaft of the power
source 12 is
coupled to a drive shaft 16 (e.g., through a transmission or other
intermediary devices). The
drive shaft 16, in turn, transfers the power to two or more wheels 14.
100031 For a fire truck, the power source 12 may also be configured to drive a
main water
pump 40 for the vehicle. The main pump 40 is used to pump water from a source
(e.g., a fire
hydrant, a pool, a lake, etc.) so that the water or a foam can be output
through hoses or
stationary nozzles or deck guns.
[0004] As illustrated, in addition to the wheels 14, and the main water pump
40, the power
source 12 further provides power to other devices. This is typically done by
rotational
transfer energy through belts and pulleys, or through direct drive through a
power shaft.
Vehicles powered by an internal combustion engine (e.g., gasoline engine,
diesel engine)
often include a serpentine belt. The serpentine belt is routed to engage an
input pulley driven
by the internal combustion engine and one or more output pulleys that are
coupled to
peripheral devices. The peripheral devices that are powered by the internal
combustion
engine represent parasitic loads. These parasitic loads include the chassis
main alternator 18,
main air conditioning (HVAC) compressor 20, as well as secondary alternators
and
compressors, hydraulic and pneumatic motors, secondary water pumps used for
fire
suppression, etc.
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100051 The main and secondary alternators convert a portion of the power
output of the
internal combustion engine to electrical power. The alternator 18 is coupled
to one or more
batteries 22. This electrical power is used to run various devices such as
sensors, pumps, on-
board computers, fans, etc. The compressor 20 may be a compressor for a vapor
compression
refrigeration system 24. The refrigeration system 24 further includes an
evaporator 26, a
condenser 28, and an expansion valve 29. Additional devices, such as fans,
pumps, and
electronics may also draw power from power source 12, either directly or
through alternator
18. The internal combustion engine must be sized to provide power both to the
parasitic
loads and to the power train of the vehicle to drive the wheels. As such, the
internal
combustion engine is generally designed to be larger and have a larger power
output than is
needed to simply propel the vehicle.
(00061 Further, when the vehicle is stationary, the internal combustion may be
idled to
provide power to the parasitic loads. While idling, the large internal
combustion engine may
produce an excessive amount of noise and combustion pollution, as well as
consume large
amounts of fuel. Such idling periods may be especially significant for medium
and heavy
duty rescue and utility vehicles, such as fire trucks, delivery vehicles,
ambulances, cranes,
etc.
[0007] The usage of these non-high energy systems have typically higher duty
cycle times
than that of the high energy load requirements of the drive wheels and high
power devices
such as main fire pumps and therefore do not require the larger power and fuel
consuming
spent on a typical main power plant.
[0008] Fire trucks often include an auxiliary power unit in the form of a
diesel generator.
The generator can be used to provide power to hydraulic equipment, pumps, and
other
devices. As shown in FIG. 2, it is known for a system 30 to include a
secondary power
source 32 that is added to the vehicle 12 to supplement the first power source
12. When
additional electrical current or additional heating and/or cooling is required
by the vehicle,
the secondary power source 32 is activated while the main power source 12 is
operating, thus
providing the additional energy or mechanical force necessary to keep such
described
systems operating.
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(0009] This type of configuration may include a transfer switch 34 that
provides for the
power balancing between the main power plant alternator 18 and the secondary
power source
32 for the prevention of over current over voltage difference caused by two
independent
electrical sources.
[0010] Mechanical power balancing must also be provided for through the use of
solenoids
36 as illustrated to protect the main power plant air conditioning compressor
20 from
pneumatic surges caused by a secondary power plant air conditioning compressor
38.
[0011] It would be desirable to provide an improved power system for a vehicle
that
reduces the load placed on the main power source from parasitic loads.
SUMMARY
[0012] One embodiment of the invention relates to a power system for a
vehicle. The
power system includes a first power source that is configured to provide power
to the wheels
of the vehicle. The power system further includes a second power source, an
electrical
system powered by the second power source, and an accessory powered by the
second power
source. The first power source does not provide power to the electrical system
or to the
accessory.
[0013] It is to be understood that both the foregoing general description and
the following
detailed description are exemplary and explanatory only, and are not
restrictive of the
invention as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] These and other features, aspects, and advantages of the present
invention will
become apparent from the following description, appended claims, and the
accompanying
exemplary embodiments shown in the drawings, which are briefly described
below.
[0015] FIG. 1 is a block diagram of a conventional vehicle drive system.
[0016] FIG. 2 is a block diagram of a prior art hybrid vehicle drive system.
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100171 FIG. 3 is a block diagram of a hybrid vehicle drive system according to
an
exemplary embodiment.
100181 FIG. 4 is a block diagram of a hybrid vehicle drive system according to
another
exemplary embodiment.
DETAILED DESCRIPTION
[0019) The following description refers to an improved power system for a
medium or
heavy duty vehicle. More specifically, the improved power system is described
installed in a
fire truck, such as a pumper truck, ladder truck, airport crash tender, etc.
However, it should
be understood that the innovative features are applicable to other heavy and
medium duty
vehicles, such as mobile trunk-mounted cranes, ambulances, utility vehicles,
delivery
vehicles, tanker trucks, refrigerator trucks, etc. The improved power system
may also be
useful for light vehicles, such as passenger vans, cars, trucks, SUVs, etc.
[00201 A second power source is added to the vehicle chassis. The second power
source is
configured to power all of the vehicle's parasitic loads, allowing the primary
power source to
be designed and optimized to provide power to the vehicle drive train. These
parasitic loads
include the chassis main and secondary alternator, main and secondary air
conditioning
(HVAC) compressor (s), hydraulic and pneumatic motors, and secondary water
pumps used
for fire suppression.
[00211 The main power source is therefore used only when the vehicle is
required to
provide power to the drive train wheels or larger high power required devices
on the chassis.
The removal of these parasitic loads allows an operator of the vehicle that
ability to turn off
the main power source when high power requirements are not needed but allow
the vehicle to
function in all other ways. The second power source allows other vehicle
functionality to
continue, including providing power for non-high energy loads such as heating,
air
conditioning, interior and exterior lighting, communications and infotainment,
chassis and
body control functions such a windows, door locks, and other related safety
and convenience
features as once provided for by the main power plant.
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100221 By providing a secondary power source, the main power source can be
downsized,
resulting in a proportionately smaller engine and reduced fuel and emission
consumption. By
adding a secondary power source to the vehicle, all parasitic loads can be
removed from the
main power source.
[00231 Referring to FIG. 3, a schematic block diagram of vehicle 110 with an
improved
power system is shown according to an exemplary embodiment. The vehicle 1 10
includes
main power plant or power source 112. According to an exemplary embodiment,
the main
power source 112 is a diesel engine, but in other embodiments may also be a
gasoline engine
or any other suitable portable power source. The main power source 112 is
coupled to a drive
shaft 116 (e.g., through a transmission or other intermediary devices). The
drive shaft 116, in
turn, transfers the power to two or more wheels 114. The vehicle 110 may have
one pair of
driven wheels 114 coupled to the drive train or may have multiple pairs of
driven wheels 114
(e.g., one or more pairs of rear wheels may also powered through the drive
shaft 116).
10024] The main power source 112 may also be configured to power a main pump
118 for
the vehicle 110. The pump 118 may be configured to pump water from a source
(e.g., a fire
hydrant, a pool, a lake, etc.) so that the water or a foam can be output
through hoses or
stationary nozzles or deck guns.
[00251 The vehicle 110 further includes a secondary power source 120.
According to an
exemplary embodiment, the secondary power source 120 is a diesel engine, but
in other
embodiments may also be a gasoline engine or any other suitable portable power
source (e.g.,
fuel cells, etc.). The secondary power source 120 can be mounted any suitable
location on
the vehicle, such as behind the cab of the vehicle 110.
100261 The secondary power source 120 provides power for all of the vehicle's
parasitic
loads by powering one or more accessories. The secondary power source 120
allows other
vehicle functionality to continue when the vehicle is stopped without running
the main power
source 112. The additional functionality is usually non-high energy loads that
can be
powered by a smaller power source than is needed to propel a vehicle.
According to one
exemplary embodiment, the secondary power source 120 is used to power an
electrical
system 130 and an HVAC system 140.
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100271 The electrical system 130 may be, for example, a 12 volt or 24 volt DC
system
typical for a fire truck or may be a higher voltage system, such as a 48 volt
or 60 volt DC
system. An alternator 132 is coupled to the secondary power source 120. The
alternator 132
is driven by the secondary power source 120 to produce an alternating current
which can be
converted to a direct current with a device such as a rectifier. The
electrical power from the
alternator 132 is used to charge one or more batteries 134. Depending on the
size and
function of the vehicle 1 10, the batteries 134 may vary in type and number.
For example, the
batteries 134 may be lead acid batteries or another suitable electrochemical
batteries (e.g.,
nickel-metal hydride (NiMH), lithium-ion, lithium-ion polymer, etc.).
According to one
exemplary embodiment, the vehicle 112 includes six lead acid batteries. The
electrical
system 130 is used to power a wide variety of devices on the vehicle,
including hotel loads
(e.g., fans and vehicle lighting), communications and infotainment devices
(e.g., radios, GPS
units, laptop computers, etc.), interior and exterior vehicle lighting,
chassis and body control
functions (e.g., power windows, power door locks, seat adjustment motors,
etc.), and safety
devices (e.g., seat occupant sensors, airbag deployment sensors, etc.). The
electrical system
130 further provides power to devices associated with the vehicle's internal
combustion
engines (e.g., power sources 112 and 120) including fluid pumps, sensors,
motors, and on-
board computers. The electrical system 130 may also be used to power other
devices for a
fire truck such as sirens, water pumps, hydraulic pumps, ladder controls, etc.
[00281 The HVAC system 140 may be, for example, a vapor compression
refrigeration
system typically used in a vehicle. The HVAC system includes a compressor 142,
a
condenser 144, an expansion valve 146 and a evaporator 148. The compressor 142
may be,
for example, a compressor that is commonly used in automotive applications and
coupled to
the main power source of the vehicle.
[00291 According to an exemplary embodiment, the secondary power source 120
may
further be coupled to an AC generator 150 to provide AC electrical power. The
AC generator
150 is capable of outputting AC power at 110, 220, and 440 volts at single or
multiple phases
depending on the application. The AC power may be used, for a variety of
emergency tools
such as hammers, drills, hydraulic rescue tools, exhaust fans, etc. In one
exemplary
embodiment, the vehicle 110 may be configured to act as mobile electrical
power plant. For
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example, in emergency areas, the vehicle 1 10 may be able to provide
electrical power for
tents or other triage areas (e.g., to power medical instruments, to provide
heating and cooling,
to power lights, etc.) or even to provide electrical power to one or more
homes.
100301 Similar to existing vehicle power systems, rotational energy from the
secondary
power source 120 can be transferred to the accessories and peripheral devices
through belts
and pulleys (e.g., a serpentine belt), through direct drive through a power
shaft, or via another
device (e.g., a power take-off, a gearbox, a chain and sprocket system, etc.).
According to an
exemplary embodiment, the alternator 132 and the compressor 142 are driven by
the
secondary power source 120 through a belt and pulley system. The AC generator
150 is
coupled to the output shaft of the second power source 120.
[00311 The electrical system 130 can be configured to interface with an
electrical grid. Fire
trucks are generally plugged into the electrical grid (e.g., shore power) when
they return to
the station after an emergency call. With the use of the secondary power
source 120, vehicle
1 10 can recharge the batteries 134 of the electrical system 130 on the drive
back to the
station.
[00321 The secondary power source 120 can easily be retrofitted to existing
vehicles, such
as shown in FIG. 1. Fire trucks generally feature diesel generators that are
mounted in
existing space behind the cab of the vehicle. The secondary power source 120
can be
installed in this location and be used to remove parasitic loads from the main
power source
112. The chassis electrical alternator can be removed from the main power
source 112 and
integrated into the secondary power source 120 or may be removed and replaced
by another
alternator coupled to the secondary power source 120. Similarly, the chassis
air conditioning
compressor can be removed from the main power source 112 and integrated into
the
secondary power source 120 or may be removed and replaced by another
compressor coupled
to the secondary power source 120.
100331 Many emergency situations to which a vehicle 110 such as a fire truck
may be
called do not involve a fire that needs to be suppressed. Fire trucks are
often called to the
scenes of traffic collisions, medical emergencies, and other emergency
situations. Therefore,
the main pump 118 of the vehicle 110 may not be needed for the entirety of the
call. The use
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of the secondary power source 120 to power the parasitic loads and the removal
of these
loads from the main power source 112 can allow for near complete chassis
functions while
the main power source 112 is shut down.
100341 The removal of the parasitic loads increases available power to the
wheels 114
through the drive train and to the main pump 118 from the main power source
112. Because
both the main power source 112 and the secondary power source 120 can be sized
and
configured for different power needs and duty cycles, fuel consumption can be
reduced.
Depending on the use of the vehicle, fuel consumption by 70%, compared to a
traditionally
configured vehicle, as shown in FIG. 1. The reduced fuel consumption further
results in a
reduction in the exhaust emissions produced by the vehicle. In addition, a
reduction in the
amount of idling time for the main power source 112 greatly reduces the wear
on the main
power source 112, reducing maintenance costs and extending the life of the
main power
source 112.
[0035] Unlike a system that runs in parallel with an existing system, as shown
in FIG. 2, the
vehicle 110 including the secondary power source 120 exclusively powering the
parasitic
loads does not require additional transfer switching or additional mechanical
clutching or
solenoid activation to balance the electrical and air conditioning systems.
[0036] The vehicle 110 including the secondary power source 120 is modular in
design and
allows for future additional adaptation of parasitic loads. Additionally, if
the power drawn by
parasitic loads exceed the power capabilities of the secondary power source
120, the
secondary power source 120 can be replaced with a larger unit while the main
power source
112 remains unchanged.
[0037] The use of the secondary power source 120 increases electrical DC
capacity beyond
typical chassis alternator configurations for conventional vehicles. Further,
the use of an AC
generator 150 coupled to the secondary power source 120 provides a method of
supplying
AC power at 120 VAC, 240 VAC, or even 440 VAC.
[0038] The main pump 118 is shown in FIG. 3 as being powered by the main power
source
112, but in other embodiments, the main pump 118 may be powered by the
secondary power
source 120. In still other embodiments, as shown in FIG. 4, the main pump 118
may be
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powered by a third power source 160, such as a diesel engine. In this way, the
main power
source 112 can be optimized for driving the wheels 114 and the third power
source 160 can
be optimized to operate a high-power pump.
100391 While the vehicle is described as having a conventional drive system,
which
includes a mechanical connection between the internal combustion engine or
other power
source and the wheels, in other embodiments, there may not be a direct
mechanical
connection between the power source and the wheels. Instead, the alternator
may be used to
provide power to the batteries and the wheels may then be driven by electric
motors that draw
power from the batteries.
[00401 The construction and arrangements of the vehicle power system, as shown
in the
various exemplary embodiments, are illustrative only. Although only a few
embodiments
have been described in detail in this disclosure, many modifications are
possible (e.g.,
variations in sizes, dimensions, structures, shapes and proportions of the
various elements,
values of parameters, mounting arrangements, use of materials, colors,
orientations, etc.)
without materially departing from the novel teachings and advantages of the
subject matter
described herein. Some elements shown as integrally formed may be constructed
of multiple
parts or elements, the position of elements may be reversed or otherwise
varied, and the
nature or number of discrete elements or positions may be altered or varied.
The order or
sequence of any process, logical algorithm, or method steps may be varied or
re-sequenced
according to alternative embodiments. Other substitutions, modifications,
changes and
omissions may also be made in the design, operating conditions and arrangement
of the
various exemplary embodiments without departing from the scope of the present
disclosure.
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